1. Field of the Invention
The invention relates to a device for feeding tablets, or the like, to blisters made in a travelling sheet of synthetic material, and for example the blisters of cards thermoformed in a web of synthetic material subsequently receiving a closure film.
Such devices are disposed above the trajectory of travel of a blister sheet, moved for example by a belt conveyor.
2. Discussion of Related Art
The current devices use vibratory feeders which select, orient, and dispatch the tablets to a means for filling the blisters, comprising dispensing means and distributing means, such as brushes, rectilinear or rotary, guaranteeing the entry of each tablet into a blister.
By reason of the diversity of shapes and dimensions of the tablets and of the orientation of the blisters, namely, parallel, transverse, or inclined with respect to the direction of movement of the sheet, each dispenser can dispense only one or perhaps two types of tablets. Moreover, it is in general specific to a packaging installation and can no longer be transferred over to another installation. A consequence of this is to limit an installation to the dispensing of certain tablets and to not be able to adapt it rapidly for the dispensing of other tablets, when demand for these latter becomes greater.
To this drawback, which involves increasing the number of specialized installations so as to cope with diversified demand, are added those resulting from the dispensing conditions. Specifically, in current devices the stream of tablets is poorly controlled, so that chips and dust may form in the dispensing circuit, through joggling or jamming which engender damage to the tablets. This causes the provision of incomplete packaging or of packaging containing defective tablets and/or dust affecting not only the aesthetic appearance, but also the hygiene of the packaging.
Such is the case in the document DE-A-9 842 273 in which the hopper of a storage reservoir dispenses a batch of tablets under gravity into a temporary reservoir formed in the distributing device, upstream of rectilinear distributing brushes, and in which the surplus product is sucked up and recycled.
The object of the present invention is to remedy these drawbacks by providing a device affording complete and regular filling, without damaging the dispensed tablets, and which can very rapidly be transferred from one installation to another, while being able to receive tablets of different shapes and dimensions, thereby improving the loading schedule of each packaging installation, and that of a plant.
To this end, the device according to the invention consists of a single enclosure containing and carrying the storage reservoir, the dispensing means, and the distributing means consisting of cylindrical and rotary brushes. The dispensing means consists of two parallel flaps which, forming the bottom of the reservoir and delimiting a buffer bay, are inclined with respect to the horizontal, downward in the upstream sense, come into closure contact against the upstream transverse wall of the enclosure, near to the blister sheet, are translationally mobile and are linked, by their posterior ends, to independent means able to move them in one direction or the reverse, the control of the means of opening and closing each flap reacting, in respect of the upper flap, to a volumetric sensor detecting the quantity of tablets accumulated in the buffer bay and, in respect of the lower flap, to the sensor disposed above the travelling sheet, upstream of the first brush, and detecting the quantity of tablets accumulating against the first brush.
With this device, when the quantity of tablets accumulated against the first brush reaches a specified minimum volume, the corresponding sensor triggers the sliding of the lower flap and thus causes all or some of the content of the buffer bay to be emptied in small waves as close as possible to the filling zone.
Likewise, when the content of this bay reaches a minimum volume, the sensor associated therewith opens the upper flap, so that the latter allows some of the tablets contained in the reservoir to enter the bay. As soon as the maximum volume which can be accommodated in the bay is reached, the same sensor closes the flap.
It follows from this that the tablets stored in the reservoir are subjected to no vibration or movement which might damage them, through volume and weight of the tablets.
Advantageously, the lower end of the lower flap is, in the closure position, substantially in the horizontal diametral plane of the first brush.
Thus, transfers, respectively from the reservoir to the bay and from the bay to the distributing station, take place solely under gravity over small distances, and in small quantities, so that the kinetic energy imparted to the tablets is insufficient to damage them and form fragments and dust.
In one embodiment, the enclosure is fixed by dismantlable means on the vertical platen of a box which can be moved vertically on the runners of a chassis, disposed laterally to the conveyor moving the blister sheet, said box containing, for each of the brushes of the enclosure, an electric drive motor whose output shaft is equipped with means for rotational and translational linkage and with positioning means, all able to cooperate with complementary means made at the posterior end of the drive shaft for each brush.
This enclosure which will be fitted onto the power take-offs of the motorization disposed in the outer box, is interchangeable and may be specific to a product, thereby eliminating any risk of cross-contamination. This removability facilitates cleaning thereof and the cleaning of the station which can very rapidly be freed, all the more easily since all the elements in contact with the tablets are dismantlable.
Other characteristics and advantages will emerge from the description which follows with reference to the appended schematic drawing.